Brain and Mind Centre, The University of Sydney, Sydney, Australia.
Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK.
Amyotroph Lateral Scler Frontotemporal Degener. 2020 Aug;21(5-6):396-402. doi: 10.1080/21678421.2020.1733020. Epub 2020 Feb 28.
The corpus callosum is a site of pathological involvement in the neurodegenerative disorder amyotrophic lateral sclerosis (ALS). The corpus callosum shows widespread cortical connectivity topographically distributed along its length. Initial limb weakness in ALS is typically unilateral, becoming bilateral with disease progression. The precise anatomical substrate for this spread is uncertain. The present study investigated sub-regional variations in corpus callosum integrity in ALS, and whether these reflect a relationship with the development of unilateral or bilateral limb weakness. Sporadic ALS patients were categorized into unilateral ( = 14) or bilateral ( = 25) limb weakness at the time of assessment and underwent diffusion tensor imaging. Probabilistic bundle-specific tracking was carried out using MRtrix and TractSeg to parcellate the corpus callosum into seven anatomical segments (rostrum; genu; rostral body; anterior midbody; posterior midbody; isthmus; splenium). White matter tract integrity was assessed in all segments and compared with MRI data acquired from 25 healthy controls. In the combined patient group, the most prominent differences in diffusivity metrics were in the rostral body, posterior midbody and isthmus of the corpus callosum ( < 0.04). Loss of corpus callosum integrity was most prominent in the sub-group with unilateral limb weakness at the time of scanning ( < 0.05). Corpus callosum involvement in ALS is detectable across multiple segments, in keeping with a widespread cortical distribution of pathology. The association of unilateral limb weakness with greater loss of corpus callosum integrity informs connectivity-based hypotheses of symptom propagation in ALS.
胼胝体是神经退行性疾病肌萎缩侧索硬化症（ALS）的病变部位。胼胝体显示出广泛的皮质连接，沿着其长度呈地形分布。ALS 最初的肢体无力通常是单侧的，随着疾病的进展变为双侧。这种扩散的确切解剖学基础尚不确定。本研究调查了 ALS 中胼胝体完整性的亚区域变化，以及这些变化是否反映了与单侧或双侧肢体无力发展的关系。
在评估时，将散发性 ALS 患者分为单侧（ = 14）或双侧（ = 25）肢体无力，并进行弥散张量成像。使用 MRtrix 和 TractSeg 进行概率束特异性跟踪，将胼胝体分为七个解剖节段（嘴部；膝部；体部；前体中部；后体中部；中部；压部）。在所有节段评估白质束完整性，并与 25 名健康对照者获得的 MRI 数据进行比较。
在联合患者组中，弥散度指标最显著的差异出现在胼胝体的体部、后体中部和中部（ < 0.04）。在扫描时单侧肢体无力的亚组中，胼胝体完整性的丧失最为明显（ < 0.05）。
ALS 中胼胝体的受累可在多个节段检测到，与病理学的广泛皮质分布一致。单侧肢体无力与胼胝体完整性更大损失的关联为 ALS 中症状传播的连接假说提供了信息。
